The Walk Free Foundation's "Global Slavery Index" found that an estimated 29.8 million people around the world were trafficked for labor or sex work.

India topped the list in sheer size, with an estimated 13,300,000 to 14,700,000 people enslaved. It accounts for nearly half of all modern-day slaves in the world.

The index placed Mauritania at number 1 for a different reason: With a population of just 3.8 million, it has an estimated 140,000 to 160,000 people enslaved — due mainly to child marriage and chattel slavery (the buying and selling of human beings).

"Today some people are still being born into hereditary slavery, a staggering but harsh reality, particularly in parts of West Africa and South Asia," the report noted.

"Other victims are captured or kidnapped before being sold or kept for exploitation, whether through 'marriage,' unpaid labor on fishing boats, or as domestic workers. Others are tricked and lured into situations they cannot escape, with false promises of a good job or an education."

"The investigation found evidence to suggest that thousands of Nepalese, who make up the single largest group of labourers in Qatar, face exploitation and abuses that amount to modern-day slavery, as defined by the International Labour Organisation, during a building binge paving the way for 2022," the Guardian wrote.